High level tetracycline resistance (Tcr) in urogenital microorganisms including Neisseria gonorrhoeae, Mycoplasma hominis, Ureaplasma urealyticum and Gardnerella vaginalis is strongly associated with the presence of the tetM resistance determinant. This determinant was first described in enteric streptococci, is found in both oral and enteric species, is usually associated with the chromosome and is often located on a conjugative transposon. It has now become established not only in gram positive bacteria, but gram negative and cell wall-free species as well. We will clone the Tcr tetM gene from Neisseria gonorrhoeae, Mycoplasma hominis, Ureaplasma urealyticum and Gardnerella vaginalis and compare the genetic organization, DNA sequences and protein products with the previously characterized tetM from the well characterized tetM determinant isolated from Streptococcus agalactiae (Group B) and the recently sequenced tetM from S. pnuemonae. We will examine the DNA sequences flanking the structural tetM determinant to determine if it is in the same location in all different strains or if it varies from strain to strain and species to species. We will examine the prevalence and distribution of Tcr in urogenital bacteria and determine the mechanism(s) of transfer from strain to strain and species to species. This will provide information on the movement of antibiotic resistance genes between unrelated bacteria and the comparison of a single determinant at the molecular level, in gram positive, gram negative and cell wall-free bacteria.